Rock drill bit



n- 1 P. B. BROWN 2,776,819

ROCK DRILL BIT Filed 00$. 9, 1953 2 Shets-Sheet 1 v Fig. 2. 9

INVENT OR PHILIP B. BROWN 4d BY ATTORNEY P. B. BROWN Jan. 8, 1957 Filed 195s RocK DRILL BIT Philip B. Brown, Hidalgo de Parral, Mexico Application October 9, 1953, Serial No. 385,209

2 Claims. (Cl. 255-63) This invention relates to improvements in percussion type of rotary rock drilling bits.

The primary object of this invention is the provision of an improved rock drilling bit which has a rapid and economical drilling action; improved features being provided by means of which, without resharpening, the bit will drill holes in rock deeper and with greater rapidity than with conventional rock drill bits.

In my 'U. S. Patents 2,358,052 and 2,725,216, I have shown rock drill bits provided with means to facilitate initial penetration of rock, the shattering of it, and reaming thereof. In the present bit, I have provided means "to drill a bore of uniform diameter, having rock drilling and shattering lugs and laterally projecting wings. As

the lugs and wings become worn'the bore of the opening will naturally tend to' become smaller. I have provided other auxiliary'wings, the upper portions of which project above the first mentioned wings. After the lugs and first mentioned'wings have become worn the upper portions of the auxiliary lugs take over and ream out a rind of the work or material 'being bored and thus: maintain a bore of uniform diameter.

designate corresponding parts throughoutthe several views:

' Fig/l .is-a side elevation of the improved rock drill bit, showing application thereto of improved features in connection withcross head chisel type lugs. i

Fig. 2 is a bottom'plan view of the improved drilling bitof Fig. 1.

Figs. 3 and 4 are cross sectional views taken through the improved drilling bit, substantially on the respective -'li'njes S Y-Sand '4-4 shown-in Figs. 1 and 2 of the drawings.

1 Fig. 5 isa perspective view of the improved drilling bit of Fig. 1, showing the'manner in which the rock penetrating chisel lugs and associated parts will wear, and also showing wearupon the improved auxiliary shoulder means used therewith.

Fig.6 is a side elevation of a modified form of improved drilling bit having also associated as a part thereof, auxiliary reaming shoulders only brought into :actionafter some initial bore penetration.

Fig. 7 is a bottom plan view of the bit of Fig. 6.

Figs. 8 and 9 are cross sectional views taken substantiallyon their respective lines 8-8 and 99 shown in Figs. 7 and 6" of the drawings.

Fig. 10 is a perspective view of the bit of Fig. 6, showing wearaction on the parts of the drill bit as an incident of user United States Patent '0 lengths.

Patented Jan. 8, 1957 Fig. 11 is a vertical cross sectional view taken through one of the conical shaped pilot drilling lugs or teeth of the bit of Fig. 6, the view being enlarged and taken-sub stantially on the line 1111 shown in Fig. 7 of the drawings.

Referring to the drill bit A as shown in Figs. 1 to 5 inclusive, the same includes 'a cylindrical body portion 15 having a screw threaded socket 16 inwardly from the top surface 17 thereof for detachably receiving a drilling rod. The body portion 15 is provided with a bottom surface 18 and has an axial water passage 20 therethrough opening on the'bottom surface 18. In a drilling bit of this type it is conventional to' provide tapered rock shattering faces 21 surrounding the passageway 20. This bit A is also provided'with conventional cross head chisel lugs 24 having faces 22'-located at an angle of with respect to each other. These chisel lugs are spaced from and located beyond the central area of faces 21 and extend radially into and are integral with Wings 25. The latter are four in number and each extends axially along the body portion and radially beyond the outer circumference 26-of the body portion 15 a predetermined distance to a top edge 25'. The intersection of the sides 31 of the wings 25 with the outer surface of each of said wings provide sharp rock abraiding corners '30. The outer surfaces of the wings 25 may be fiat or arcuate as shown in the drawings. Such outer surfaces are concentric to the outer surface of the body portion and which surfaces are struck from the same radius dimension throughout their lengths.

Because of increased wear upon the outer circumference of the bit,.particularly upon the wings 25, such type of bit can only effectively drill a predetermined shallow depth because of reverse taper which forms on these wings. It isthen necessary to replace the rock bit or to sharpen it. As an improved feature of the bit A, I have provided rock removing, reaming and shattering wings 40 between the Wings 25 at aradial angleof 45 with respect to the adjacent wings 25. These Wings 40'have outer faces 41 (Fig. 2) which are struck from the same radius or lie in the same radius as the outer surfaces of the wings 25, and are concentric at their outer surfaces to the body-portion 15 and which surfaces are struck from the same radius dimension throughout their They are axially arranged along the body portion 15 with the upper ends thereof extending appreciably above the top edges 25' of the wings25. The intersection of the side surfaces 43 of said auxiliary wings 40with the outer surface 41 form reaming edges 42.

The bottom surface of the wings 40 may lie in the same plane as the bottom surface 18 of the body portion 15.

In starting a new rock bore, the drill rod is rotated, and since this is a percussion type drill bit many hundreds of impact blows per minute are applied to the bit. The shattering action commences with lugs 24 and subsequently the wings 25 also chip and penetrate the bore of the rock leaving a cylindrical bore or hole which is slightly larger in diameter than the extreme surface-- diameter of the lugs 24 and'outer surfacing of the wings 25. The auxiliary wings 40 will therefore not bind in the hole. Due to use the diameters of holes being bored tend to decrease as the'outer edges of the lugs 24 and the wings 25 wear. With conventional rock bits the wearing of the bit slows the action of pentrationand narrows the diameter of'the bore to'such'an extent that a following rock bit has to be used which is a fraction of an inch less in effective diameter. With the improved rock bit of this'invention as the lower part'of the bore narrows, due to wear upon the lugs 24, the wings-25am the lower portions of the auxiliary wings '40, the upper portions of the latter above the edges 25 take over, wear:

ing away a thin rock rind. Thereby the rock bit of this invention has a longer life than conventional rock bits and can be used for drilling a uniform diametered bore of greater depth than can be obtained with conventional rock bits because of the relation of the wings 25 and 40.

As shown at 55 in Fig. 5, the auxiliary wings 40 wear as an incident of reaming action at the outer circumference just above the bottom of the bore. It is an important feature of the invention that the auxiliary wings are so arranged as to enable quick and easy resharpening of the bit. This is accomplished by squaring up the wings 25 and 40 of the bit. This is initially done and then the central part of the bit head can be ground out surrounding the water passageway 20.

The length of the auxiliary wings stabilizes the position of the bit head to the sides of the drill hole.

When the bit head A is resharpened 1 have found that in connection with a 2 inch diametered bit it is necessary to decrease the effective bore drilling diameter of the bit by A of an inch, to provide sharp corners for the wings 25 and 40.

Referring to the form of invention B shown in Figs. 6 to 11 inclusive, the same includes a body portion 60, preferably cylindrical in formation, having a drill rod receiving screw threaded socket 61 therein. This body portion 60 has the usual water passageway 62 opening on the bottom surface 63.

The bit B presents certain novel characteristics over the form of bit A, in that it is provided with rock penetrating and removal lugs 64, at 90 apart which extend outwardly and are connected to radially extending wings 65. The wings 65 are of the same construction and for the same purpose as the Wings 25 above described. They terminate at top edges 65 and their outer surfaces are concentric with the outer surface of the body 60. These arcuate surfaces are struck from the same radius dimension throughout the lengths of the wings. They project beyond the outer circumferential surface 66 of the body portion 60, as shown in the drawings. The lugs 64 have bottom surfaces 67 at their outer ends all lying in the same plane at right angles to the axis of the drill bit. This plane is located below the plane of the bottom surface 63. The rock drilling lugs 64 each have side surfaces 68 and 69 which convergently slope towards the center of the drill bit, and also are convergently inclined from the bottom surface 63 of the drill bit body portion. This shape of the lugs 64 gives an inner sloping sharp rock pentrating edge 70 and where the sides 68 and 69 intersect with the surface 67 there are also provided sharp edges 71. While these lugs alone can furnish the initial rock drilling action I may also add to them pilot drilling teeth 80, i of conical formation. They project downwardly below the bottom surface 67 of each of these teeth and are located in an annular band between the inner and outer portions of each of the wings 65. The teeth 80 have the shape characteristics of the conical lugs of my U. S. Patent 2,725,216, dated February 5, 1956. At any point of plane intersection through the axis of each lug, the latter is in the form of a Gothic arch. Thus, the lugs are each in the form of Gothic half-spheres. Referring to the geometrical construction of these points or teeth, the base line of the tooth, as indicated at 81 in Fig. 11, lies in the plane of the bottom surface 67 of the rock penetrating lug 64. The convex curvature of the side walls 82 is struck from radii 83, the centers 84 of which are located in the Outer circumference of the base line 81; the apex 85 being determined by intersection of the surfaces struck from the radii 83. The diameter of the base 81 is less than the height 86 of the tooth 80. This type of rock penetrating tooth has been found by me to possess the necessary mass and strength for rugged rock penetrating work, the advantages of which are more fully set forth in my above identified copending application.

As a feature of the rock bit B, in common with the rock bit A, I provide auxiliary wings 90, 45 between adjacent lugs 64. Four of these are provided on the conventional 2 inch drilling bit, and they are of the same construction, and have the same characteristics as the auxiliary wing constructions 40 of the form of invention A, in that they extend lengthwise along the body portion 60 to a greater extent than the effective rock abrading and removing wings 65, as will be noted from Fig. 6 of the drawings. Furthermore, at the intersection of their outer surfaces with the side edges thereof, the wings 90 are provided with sharp corners 93. The upper portions pro ject appreciably above the top edges 65 of the wings 65 and their outer surfaces are concentric with the outer surface of the body 60. Their arcuate surfaces are struck from the same radius dimension throughout the lengths of the wings.

The use of the bit B is similar to the bit A in that the bottom surfaces of the wings 90 are located in the plane of the bottom surface 63 of the body portion of the bit and which plane is appreciably spaced from the drilling planes of the teeth and the lugs 64. It is only when the teeth 80, lugs 64, wings 65, and the lower portions of wings have been sufficiently worn that the upper portions of the auxiliary wings 90 take over and continue reaming of a shallow rind for the purpose of continuing a uniformly diametered bore. In Figure 10 is shown wear upon lugs 64 and wear 96 upon the auxiliary wings. The conical lugs have the same self-sharpening feature as pointed out in my Patent 2,725,216.

Resharpening of the bit B can be easily accomplished.

From the foregoing it can be seen that an improved drilling bit construction, of the percussion type, has been provided; the auxiliary wing and shoulder constructions of which are shaped to economically prolong the life of the bit and enable deeper drilling of bores. These auxiliary wings act with a rock removal and reaming action both on the up and down motion of the bit head and also upon rotation backward and forward.

The wings of these bits project from the side walls of the body portion of the bit to take care of the rim or outer portion to be removed as part of the bore. In comparative tests of the bit A of this application with a conventional cross head bit of the same size and material, the conventional bit after drilling 4 feet of bore was removed. It had appreciable wear upon the same and with the bit of this application a rock bore of 15 feet through the same strata was made with 3 as much wear as on the tested conventional cross head bit.

It is within contemplation of this invention to place pilot teeth on the chisel lugs of the bit A of this application in the same relationship as they are placed upon the tapered lugs of the form of invention B.

Various changes in the shape, size and arrangement of parts may be made to the form of invention herein shown and described without departing from the spirit of the invention or scope of the claims.

I claim:

1. A percussion type rotary rock drill bit comprising a body portion having a bottom surface, rock penetrating chisel shaped lugs radially arranged upon and connected to said body portion and depending below the bottom surface, said lugs at their outermost ends extending appreciably laterally of the outer side surfacing of the body portion, elongated wings provided on and extending axially of the body portion and forming lateral extensions and extending laterally of said body portion for the same distances as the lateral extensions of the respective lugs, said wings each having an arcuate outer surface which is struck from the same radius dimension along the length thereof, the sides of said wings forming with said arcuate surface sharp rock abrading edges, and elongated auxiliary rock reaming wings connected to and extending axially of said body portion at locations between the first mentioned wings and parallel thereto, the lower ends thereof lying intermediate the tops of the first wings and said lugs, and also laterally extending from the outer side surfacing of the body portion throughout their lengths for the same distance as said first mentioned wings, said auxiliary wings having arcuate outer surfaces which are struck from the same radius dimension throughout the lengths thereof, the sides of which form with said arcuate outer surfaces sharp rock abrading edges, said auxiliary wings being axially longer than the first mentioned wings and extending along said body appreciably above the upper ends of said first mentioned wings.

2. A percussion type rotary rock drill as described in claim 1 in which pilot drilling teeth of inverted substantial conical shape formation are connected to said lugs and depend therefrom at locations on said lugs inwardly of the said wings.

References Cited in the file of this patent UNITED STATES PATENTS 

